Nanotechnology: Applications in Agriculture
By - Dr. Suresh Kaushik

Introduction

The definition of nanotechnology is based on the prefix 'nano' which is from the Greek word meaning 'dwarf'. Technically, the word 'nano' means 10-9, or one billionth of something. The word nanotechnology is generally used when referring to materials with the size of 0.1 to 100 nanometers (nm). These materials display different properties from bulk materials due to their size. These differences include physical strength, chemical reactivity, electrical conductance, magnetism and optical effects. Therefore, nanotechnology is the manipulation of self-assembly of individual atoms, molecules, or molecular clusters into structures to crease materials and devices with new or vastly different properties. Hence, nanotechnology employs nanoparticles (NPs) having one or more dimension in the order of 100 nm or less.

Nanomaterials of inorganic and organic origin are used for NP synthesis by a variety of physical and chemical methods. Among inorganic materials, metal oxide NPs such as ZnO, AgO, TiO2 and MgO. Photocatalytic (ZnO, TiO2) and microbiocidal (MgO and AgO) NPs are employed for pesticide detection, degradation and control food spoilage, respectively. Other inorganic materials such as montmorillonite and other clay nanoparticles are also used as NPs known as nanoclays. Organic materials such as carbon nanotubes, lipds and polymers are versatile materials with multiple applications. The techniques for making nanoparticles are generally involved either a top-down approach or a bottom-up approach. In top-down methods, size reduction is achieved by various chemical and physical treatments such as milling, high pressure homogenization and sonication while in bottom-up synthesis, the nanostructured building blocks of the nanoparticles are formed first and then assembled to produce the final particle.

Nanoparticles are generally characterized by their size, shape, surface area, and disparity. The common techniques of characterizing nanoparticles are scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometry, X-ray diffraction (XRD), dynamic light scattering (DLS), Energy dispersive spectroscopy (EDS).

Applications in Agriculture:

Agriculture is the backbone of most developing countries. The agricultural sector is facing various global challenges such as climate change, environmental issues, urbanization, sustainable use of resources and accumulation of pesticides and fertilizers. Many countries including India have identified the potential of nanotechnology in the field agriculture such as precision farming, smart delivery systems, food industry, food processing, packaging, food safety etc. Nanotechnology has the potential to revolutionize the agriculture with new tools for the rapid disease detection and their treatments, enhancing the ability of plants to absorb nutrients, increasing the efficiency of pesticides and herbicide, etc. Indiscriminate use of pesticides and fertilizers causes environmental pollution, loss of biodiversity and emergence of agricultural pests and pathogens. Nanotechnology has potential application for alleviation of these problems. The potential applications of this technology in agriculture are:

• Delivery of nanocides i.e. pesticides encapsulated in nanomaterials for controlled release,

• Stabilization of biopesticides with nanomaterials,

• Slow release of nanomaterial-assisted fertilizers, biofertilizers and micronutrients for efficient use, and

• Field application of agrochemicals.

The goal of precision farming is to maximize output (crop yields) while minimizing input (pesticides, herbicides fertilizers) through monitoring environmental variables and applying targeted action. Precision farming makes use of computers, global positioning system (GPS), and remote sensing devices. To measure highly localized environmental conditions. Soil conditions and plant development can be determined precisely by using centralized data and subsequently fertilizer and water use can be fine-tuned to lower production costs and potentially enhance production. In future, nanotechnology-enabled devices will be used for autonomous sensors linked to a GPS system for real-time monitoring. Precision farming with the help of smart sensors will allow enhanced productivity in agriculture.

Nanoscale smart devices with novel properties could be used to identify plant health issues before these become visible to the farmers. These devices will alert the farmer to the problem. So these smart devices will act as both prevention and an early warning system. Such devices could be used to deliver chemicals in a controlled and targeted manners. For example, controlled release methods and encapsulation have revolutionize the use of pesticide and herbicides. Nanopesticides involve wither very small particles of pesticidal active ingredients or other small engineered structures with useful pesticidal properties. Nanopesticdes can increase the dispersion and wettability of agricultural formulations and unwanted pesticide movement. Basically, the nano-formulations should degrade faster in the soil and slowly in plants with residue levels faster in the soil and slowly in plants with residue levels below the regulatory criteria in foodstuffs. Nanoemulsions (suspensions of nanoscale particles) which can be either water or oil-based consists of uniform suspensions of pesticidal or herbicidal nanoparticles in the range of 200-400 nm.

There are about one thousand chemicals reported by Food and Drug Administration (FDA) as pesticide residues. Nanomaterials based nanosensors can be used to detect such pesticide residues. Nanosensors for pesticide residue detection offer high sensitivity, super selectivity, fast responses, low detection limits and small sizes. Nanomaterials, in additions to its use for pesticide and herbicide detection, have also been applied for pesticide degradation. Various techniques are being developed to make fertilizers and pesticide delivery systems in response to environmental changes. So, new research will target to make plant use water, pesticides and fertilizers more efficiently to reduce pollution and to make agriculture more environmental friendly.

In future, nanoscale devices with novel properties could be used to make agricultural system 'smart'. Smart field systems detect, locate, and report on pathogen, then apply preticides and fertilizers as needed prior on the onset of symptoms. Nanoparticles can be used as biomarkers or as a rapid diagnostic tool for detection of bacterial, viral and fungal plant pathogen in agriculture.Nanochips are types of microarrays that contain fluorescent oligo capture probes through which the hybridization can be detected.

The impact of nanotechnology in the food industry has become more apparent recently and the application include smart packaging on demand preservatives and interactive foods. Nanofoods will enhanced the nutrient quality of food through selected additives and improvements to the way the body digests and absorbs food. Developing smart packaging to optimize product shelf-life has been the goal of many companies. Nanotechnology can provide solutions in packaging and food safety e.g. increasing barrier properties (mechanical, thermal, chemical and microbe), modifying the permeation behavior of foils, improving mechanical and heat-resistance properties and sensing microbiological and biochemical changes. Nanotechnology is making an impact on the development of functional or interactive foods, which respond to the body's requirement and can deliver nutrients more efficiently. For example, nanocapsules are developed to deliver nutrients and the addition of nanoparticles to existing foods to enable increased absorption of nutrients. Similarly, nanotubes can also be used to clean ground water. For example, 2 nm diameter aluminum oxide nanofibre can be used as water purifier. Filters made from these fibres can remove bacteria and viruses from water.

In future, foods from component atoms and molecules will be manufactured, so-called "Molecular Food Manufacturing". The advancement in agricultural nanotechnology to promote 'precision farming' allowing optimum use of the natural resources with judicious farming practices; and different sensor and controlled delivery technologies could change the face of farming so-called "Nanobio-farming"

Conclusions

The extensive use of agrochemicals to boost agricultural production has polluted not only the top soil, but also ground water. Nanotechnology is becoming important for the agricultural sector. Promising results and application are already being developed in the area of delivery of pesticides, biopesticides, and fertilizers. The use of nanomaterials for delivery of pesticide and fertilizers is expected to reduce the dosage and ensure controlled slow delivery. Nanotechnology, by exploiting the unique properties of nanomaterials, has developed nanosensors capable of detecting pathogens. Apart from detection, nanotechnology also has solutions for degrading persistent chemicals into harmless components. Nanomaterials, owing to their increased contact surface area, might have toxic effects that are not apparent in the bulk materials especially in open agricultural ecosystems. The tools of nanotechnology can be employed to address the urgent issues of environmental protection and pollution. The agricultural sector should take advantage of powerful tools of nanotechnology for the benefits of mankind.

About Author / Additional Info:
Dr. Suresh Kaushik
A Biotechnology Professional from India
drsckaushik@gmail.com
http://in.linkedin.com/in/sckaushik